Subject ABR threshold data from 12 subjects

EPSRC, grant No. EP/M026728/1Reference paper: Objective measures for detecting the Auditory Brainstem Response: comparisons of specificity, sensitivity, and detection time.Subject recorded ABR data collected from 12 subjects (6 female and 6 males) ranging from 18 to 30 years of age. The stimulus was a rectangular 100 μs click delivered at a stimulus rate of 33.3 Hz through ER-2 insert phones (Etymotic, USA). The click intensities ranged from 0 to 50 dB SL (sensation level, i.e. relative to individual hearing thresholds) in steps of 10 dB. The behavioural thresholds were estimated using a simple ‘up-down’ approach where the click intensity was reduced in steps of 10 dB for every correct response, and increased in steps of 5 dB for every missed response. ABRs were then recorded with electrodes placed at the vertex (close to Fz according to the standard 10-20 system) and the nape of the neck (reference electrode), along with a frontal electrode (low forehead) that served as ground. Measurements were obtained at a sampling rate of 10 kHz using a Cambridge Electronic Design (CED) micro 1401 data acquisition unit along with a CED 1902 amplifier. Electrode impedances remained below 5 kΩ throughout the recording. The recordings were then band-pass filtered offline from 30 to 1500 Hz with a 3rd-order Butterworth filter. Each recording was furthermore downsampled to 5 kHz, and an artefact rejection method was applied by removing 15% of the noisiest epochs, as determined by their mean square values. Approximately 3600 clicks were delivered per subject and per stimulus condition, resulting in a minimum of 3000 epochs after artefact rejection. The 30.03 ms intervals following the onset of each stimulus were saved for offline analysis in data file Subject_ABR_Data.mat